1. Field of the Invention
The present invention relates to a light flux deflecting device for use in cameras and other optical equipment as an image deviation compensating device, etc. to compensate an image deviation caused by movement of the hands and so on.
2. Description of the Related Art
A device for shifting part of a lens group, which constitutes a photographing lens, in a direction perpendicular to the optical axis can be utilized in cameras, for example, as an anti-deviation optical system which predicts an image deviation by detecting an acceleration of movement of the camera that is responsible for the image deviation, and which shifts a lens in a direction perpendicular to the optical axis in accordance with a resulting prediction signal.
One example of such a lens shifting device is disclosed in Japanese Patent Laid-Open No. 3-188430. According to the disclosed device, movement of a camera is resolved into a component in a direction to move the camera horizontally (referred to as a yaw direction hereinafter) and a component in a direction to move the camera vertically (referred to as a pitch direction hereinafter). Then, the device is constructed so as to shift a deviation compensating shift lens (referred to as a compensating lens hereinafter) in both the yaw and pitch directions independently with slide motion between guide bars and bearings or between surfaces of sliding plates or the like without causing the compensating lens to move in the direction of the optical axis. The related art disclosed in Japanese Patent Laid-Open No. 3-188430 however has drawbacks in that large sliding resistance due to friction increases energy required for shifting the compensating lens by electromagnetic force, and that, strictly speaking, the compensating lens is moved in the direction of the optical axis because of minute play (tolerances) inevitably present between the guide bars and the bearings which are fitted to each other.
Also, Japanese Patent Laid-Open No. 63-155038 discloses that a compensating lens is held by a parallel 4-articulation link while it is kept from rotating about the optical axis, movement in the direction of the optical axis caused by the parallel 4-articulation link is absorbed by a guide and an urging spring to be prevented from reaching the compensating lens, and the compensating lens is pressed by the spring against a reference plane through a ball disposed therebetween. In the related art disclosed in Japanese Patent Laid-Open No. 63-155038, however, there occurs a play, though small, in a direction perpendicular to the optical axis because a lens barrel and an annular member are loosely fitted to each other. Also, during the operation, frictional resistance is generated due to friction between the loosely fitting components. This impairs such an inherent merit, which is resulted from using the hinges of the link and the ball, that resistance in driving the compensating lens for movement is small. Further, since the compensating lens is supported by a combination of the parallel4-articulation link and the ball, the mechanism is complicated and the number of parts is increased, thus resulting in a higher cost. In addition, the above publication discloses the shift mechanism only in one direction. Even if a similar shift mechanism is provided in a direction perpendicular to that direction, it is difficult to shift the compensating lens obliquely because of the specific structural nature of the parallel4-articulation link.
Further, Japanese Patent Laid-Open No. 5-297443 discloses that, in addition to means for restraining rotation of a compensating lens about the optical axis, at least three support points in the form of balls, for example, are provided between a support frame and a fixing frame for the compensating lens and are pressed by pressure applying means to reliably and accurately hold the compensating lens perpendicular to the optical axis when the lens is shifted. In the related art disclosed in Japanese Patent Laid-Open No. 5-297443, however, sliding resistance due to friction is not sufficiently small because the means for restraining rotation of the compensating lens about the optical axis utilizes sliding motion of mutually fitting members, such as a guide bar and a bearing, or a slot and a pin. Further, since the at least three balls and the pressure applying means are provided in addition to the means for restraining rotation of the compensating lens about the optical axis, the mechanism is complicated and the number of parts is increased, thus resulting in a higher cost.
Japanese Patent Laid-Open No. 7-294975 discloses that a compensating lens is moved back and forth by feed screws in the X-axis (yaw) direction and the Y-axis (pitch) direction independently, and a roller is interposed between a compensating lens frame and a movable member to avoid interference between movements of the compensating lens in the respective driving directions, thereby enabling the compensating lens to shift in all directions. Further, a ball is interposed between the compensating lens frame and a base, and the compensating lens frame is urged by a spring to be held in place to prevent the compensating lens from tilting when it is shifted. In the related art disclosed in Japanese Patent Laid-Open No. 7-294975, however, resistance produced when shifting the compensating lens is still large because a sliding frictional resistance generating portion exists between a guide shaft and a guide member for the movable member, and rolling frictional resistance is additionally generated due to the roller contact between the compensating lens frame and the movable member. With the further provision of a support mechanism using the ball, the entire mechanism is complicated and the number of parts is increased, thus resulting in a higher cost.
There have been made proposals which are applicable to support devices for optical elements, such as a shift lens, with an expectation enabling the drawbacks of the above-described conventional devices to be solved, i.e., enabling a decrease of resistance in driving the optical element to be realized with a simpler construction. As one example of those proposals, Japanese Patent Laid-Open No. 5-15121 discloses an optical pickup device for reading a signal recorded on a recording surface of an optical disc. More specifically, in a structure movably supporting an object lens used to condense a laser beam onto the recording surface of the optical disc, a joint portion supported by a pair of parallel arms is provided in spaced relation to a base, link arms crossing each other are attached to project one surface of the joint portion opposite to the other surface thereof facing the base, and a movable portion holding a lens holder is provided at tip ends of the link arms. With this structure, the object lens is supported movably in a focusing direction parallel to the optical axis and in a tracking direction perpendicular to the optical axis.
Meanwhile, a track ball has been hitherto employed in an input device, such as a pointing device, for computers. With the track ball, rotation of a spherical body is mechanically converted into separate rotations about two axes, and a resulting angle of each rotation is coded by a rotary encoder, followed by being input as coordinate information to the computer.
Also, Japanese Patent Laid-Open No. 4-125723 discloses that when an operator rolls a dome-shaped slider by the finger tip to move it, a change in magnetic field of a permanent magnet attached to the slider is detected by an electromagnetic transducer, and a cursor or pointer on a display screen is moved in accordance with an output of the electromagnetic transducer.
Further, Japanese Patent Laid-Open No. 8-87375 discloses that an operating stick is fixed to the center of a cross-shaped flexible board, and strain gauges are formed on lower surfaces of four elongated pieces of the flexible board. When an operator applies force to an upper end of the resin composite stick, the four elongated pieces are elastically deformed, causing the strain gauges to produce respective outputs. The outputs of the strain gauges are combined in such a manner as to be able to detect the direction and displacement of the applied force, and a cursor or pointer on a display screen is moved in accordance with a combined signal.
The above-described proposals however have drawbacks as follows. Since the device disclosed in Japanese Patent Laid-Open No. 5-15121 has a double structure of4-articulation link which comprises the pair of parallel arms having four hinge portions arranged side by side in the same direction and the link arms crossing each other, a region where the movable portion is allowed to move is limited narrowly due to restrain conditions imposed by the joint portion which is interposed between the parallel arms and the link arms. Accordingly, if such a double structure is applied to a shift device for moving a lens in a plane perpendicular to the optical axis, a support device capable of realizing a desired shift region of the lens would be necessarily increased in size.
For the input device using the track ball or disclosed in Japanese Patent Laid-Open No. 4-125723, the input operation is effected upon the operator's finger tip moving on the spherical surface. For the input device disclosed in Japanese Patent Laid-Open No. 8-87375, the input operation is effected upon the stick being tilted down about the center of rotation by the operator's fingers. In each of those input devices, considering touch and feel from the viewpoint of the operator, the input operation is not matched with movement of the cursor or pointer on the display screen in the form of a plane (i.e., planar movement). Further, since the track ball is subjected to variations of torque due to mechanical losses such as friction caused in the shaft support portion and the portion for transmitting rotation to the rotary encoder, smoothness of the input operation is impaired and a good feel cannot be achieved in the input operation.
With the input device disclosed in Japanese Patent Laid-Open No. 4-125723, since the dome-shaped slider has a large contact area when it moves along a spherical surface, smoothness of the input operation is impaired due to frictional resistance and a good feel cannot be achieved in the input operation.
With the input device disclosed in Japanese Patent Laid-Open No. 8-87375, since the flexible board having the strain gauges has a limited number of elongated pieces (i.e., has the crossed form), resistance force imposed from the stick varies depending on a direction in which the stick is tilted down. Further, since the flexible board, to which the resin composite stick is fixed, is forced to deform elastically, i.e., it is subjected to unstable deformation, an operation feel is basically inferior. Accordingly, a good feeling cannot be achieved in the input operation.